The next order contribution to electromagnetic radiation originates from a change of the electric quadrupole moment \(Q_{\alpha \,\beta }\) , where indices \(\alpha \)  and \(\beta \)  refer to Cartesian components (contribution coming from a time variation of the magnetic dipole moment remains of the same order) [1]}
\(P = \frac{1}{180\, c^5} \sum _{\alpha ,\beta } (\dddot{Q}_{\alpha \,\beta })^2\, \,,\) 
